Combination coal-wood electric range



Oct. 11, 1938. .H. T. BURROW 2,133,184

COMBINATION COAL-WOOD ELECTRIC RANGE I Filed May 31., 1935 3 Sheets-Sheet 1 E C. i

Oct. 11, 1938. H, BURRQW 2,133,184

COMBINATION COAL-WOOD ELECTRIC RANGE Filed May 31, 1935 3 Sheets-Sheet 2 Tb m 5 Q L I w *1 t3 I Q W *0 Q N NN' "st Q95 l\- mm Q R w, $1M; to 0 w v I v Inventor M3355 fl/"Ze/iffiW/o w,

Oct. 11, 1938. HT. BURROW COMBINATION COAL-WOOD ELECTRIC RANGE Filed May 31, 1955 3 Sheets-Sheet 3 Patented Oct. 11, 1938 PATENT OFFICE 2,133,184: COMBINATION COAL-WOOD ELECTRIC, RANGE Herbert T. Burrow, Beaver Dam,

Wis., assignor to Malleable Iron Range Company, Beaver Dam, Wis., a corporation of Wisconsin Application May 31, 1935, Serial No. 24,409

8 Claims.

My invention relates to improvements in combination coal-wood and electric ranges.

In ranges using solid fuel such as coal or wood, the products of combustion pass near or partly around the oven and thus heat the same. The walls of the oven are usually made of sheet steel which conducts the heat readily and thus makes possible an efiicient design. In electric ranges,

. and to some extent in gas ranges, the heat is generated within the oven'and, therefore, such heat as is conducted through the walls thereof from the inside to the outside represents a loss. To reduce the loss to a minimum and insure eflicient operation, it is desirable to protect the walls with heat insulating material, 1. e. to construct them'so that they are poor conductors of heat. Thus the requirements for the efficient operation of coal or wood heated ovens and of electrically heated ovens are diametrically opposite, and in designing a combination range or stove in which the structure is to be kept within reasonable limits of size by providing a single oven instead of two ovens, or in any case an oven adapted to be heated either by the burning of solid fuel or by an electric resistance element, considerable inherent difficulty is encountered.

The general object of my invention is to over-.

come this difficulty by providing a range or stove in which the same oven may be heated efficiently either by burning solid fuel such as coal or wood, or by generating the heat within the oven, by the use of an electric resistance element. Such ranges have the advantage of providing excess heat which may be utilized to heat the kitchen in winter when fuel is being burned in the range, and of operating electrically in summer with a minimum of heat dissipated into the room, during those periods when it is desired to keep the kitchen as cooI as possible.

Objects contributory to the sired are as follows:

To provide a range having a single oven which may be efiectively heated either by gaseous products of solid fuel, or by electricity within the oven, and having also so-called coal burners with lids, 'on the top, as well as electric units on the top, whereby two substantially complete ranges of different types are combined in one structure without exceeding the conventional requirements for a single range from the standpoint of size.

To provide an improved range having an oven with an airspace or duct around it in communication with a fire box, and a draft controlling the fiow of air from said duct to a flue, whereby whensaid draft is open and fuel is burning 1; said fire general result de I box, said oven is efficiently heated by the products of combustion flowing over it, and when said draft is closed and with no fire in said fire box said air space becomes a heat insulator for said oven, enabling the latter to be heated efliciently from within, by an electric resistance element.

To provide a somewhat isolated and air cooled chamber or compartment for the switch assembly whereby the switch contacts are not affected adversely by the heat from the oven or the electric burners.

To provide improved heat insulating means for various parts of the range structure avoiding metal to metal contact between the oven proper and the outside frame.

Various other objects and advantages will be apparent from the description hereinafter given of a commercial embodiment of the invention as illustrated in the drawings, in which:

Fig. 1 is a front elevation of a range, with part Fig. 7 is a perspective view of one end 01' the range with certain parts broken away; and

Fig. 8 is a perspective view of the oven. The range is provided with a rectangular base 50, having suitable supporting legs and having vertical side panels ll, l2, a back I3, and a-front H, with the usual oven door IS. A small door I6 is provided beneath the oven door to permit soot and dust to be removed. One end of the range, in this case the left hand end as viewed in Fig. 2, contains the the box and the right hand end near the top contains certain electrical equipment. The left hand end or fire box end is provided at the top with a small fire door. Beneath this is a fixed panel having a hinged ash shed or inner draft door and beneath this is a dust-tight drop door concealing the ash pan. These three parts or superimposed panels are not shown herein, being covered by a large or ornamental dooror fire door I I containing a draft door l8, and being shown in my application 20,661, filed May 9, 1935, and issued as Patent 2,032,252 on Februthe right hand section 22, provided with electric heating elements or units 23, preferably four in number. at the rear is the usual vertical panel 24, which, if desired, may be high enough to have a horizontal shelf thereon near the top, such as is frequently provided. The arrangement described,

and shown more particularly in Figs. 1 and 2,

affords a balanced and pleasing design.

At the rear of the oven is a vertically arranged housing or flue located somewhat to the left of the center of the oven, as shown in Fig. 2 and- (not shown) to the front draft door l8, whereby the latter may be opened more or less, corresponding to the position of the rear door. This is shown more fully in said Patent 2,032,252 previously identified herein. Athird handle 30, substantially similar to the other two, is also provided for opening and closing the direct draft damper 3! (see Figs. 5 and 6) which damper is opened only for starting a flre with coal or other solid fuel.

Fig. 6 also shows the oven 32 in section, with the fire box chamber or ash compartment 33 at the left and another chamber or dead air enclosure 34 at the right. Special fire box castings 35 and 36 and grate bars 31 are mounted in the upper part of this flre box chamber. The products of combustion from the burning fuel bed are drawn to the right (as viewed in Fig. 6) through the passageway or chamber between the top of the oven and the top of the range, a special inclined casting 38 being provided which directs said products of combustion to and beyond the right hand side of the oven, down past which they descend. The casting or diagonal dividing wall 38 together with a vertical wall 39, separatesthe large compartment in which the oven is located, from the right hand compartment and the smaller upper compartment in which the electrical heating units are located. Said vertical wall or partition 39, which comprises heat insulating material, forms the left hand wall of the chamber 34 and provides a passageway or flue between itself and the adjacent wall of the oven. This partition consists preferably of sheet asbestos mill board reinforced by metal on opposite sides, for example vitrious enameled sheet steel 39 may be used for one side and a rust proof steel sheet 39" for the other side. The enamelled sheet constitutes the lining of said flue, being capable of effectively withstanding exposure -to the flame and hot gases. The rust proof sheet steel comprises the inner lining for the chamber 34. At

the top a strip of similar heat insulating material 39 separates the heat conducting metal portions of the vertical panel from the inclined wall 36. The products of combustion, which are indicated by arrows in Fig. 6, after passing across the top of the oven and down around the side and under the bottom thereof, are drawn off through the opening or back flue 46 which opens into the lower end of the rear flue 25, shown in dotted lines.

The bottom duct is closed at its left hand end by a vertical sheet metal partition 40' which also Projecting from the top of the stove makes the ash compartment at the left, air tight.

It will be seen that the products of combustion just referred to, are in contact with oven walls made of metal and hence of good heat conducting material, thereby insuring high efficiency when coal or other solid fuel is used. The outlet from said rear flue25, as previously stated, is controlled by the damper 26 whereby the draft may be regulated.

In addition to the vertical heat insulating partition 39 in the right hand side of the oven there is also another vertical heat insulating partition 4|, made preferably of asbestos mill board, reinforced with asheet of metal 4|", comprising the right hand wall of the chamber 34 and also forming between itself and the right hand panel l2, a fresh air flue 42 which conducts cold air from near the floor to the switch compartment 43 at the top.

The switch compartment and fresh air flue are shown also in Fig. '7, the air entering through the row of holes 44 in part of the base frame l0 and passing out through a series of openings 45 .in the switch boxchamber at the top into the upper part of the chamber 34. This fresh air duct, it will be noted, is insulatedfrom the heat of the oven by two spaced apart partitions of heat insulating material 39 and 4i. sembly 46 has the usual switch actuating levers 4'l projecting therefrom and projecting also through suitable openings in the'end panel l2, as shown for example in Fig. 4. Conductors 48 lead from the switches to the electric heating units 23, as shown in Fig. 6. It is important, to insure long life, that the switches be protected from unduly high temperatures, certain limits having been set in this regard. The switch assembly referred to is protected by being mounted adjacent the extreme side wall ofthe range at the top of the fresh air duct and is further pro-. tected by a panel of heat insulating material 49 of substantialthickness which may consist, for

example, of asbestos mill board. An additional panel of such heat insulating material 50 lines the top of the switch box chamber, as shown also in Fig. 6. Thus the maximum protection is afforded the switches.

The warm air which flows from the switch box. chamber through the openings therein into the space beneath the electric heating units 23, escapes through openings in the front wall, rear wall and end wall of the right hand side of the range. These openings are provided by notches 5f in the upper edge of the sheet metal forming these walls, which openings are concealed by the flange 62 (see Figs. 6 and 7) which extends The switch asdownwardly and outwardly from the top surface of the range.

When the oven is to be heated electrically, the heating unit 53, shown in Figs. 4 and 6, is employed. Said unit is connected to the circuit by a plug connector 64, shown in Fig. 4, from which connector the conductors extend upwardly through a compartment 68 at the rear of the oven. Thus the connection with the electric oven heating unit is made at the right hand rear corner of the oven where the heat is a minimum and where the electrical connections do not have'to pass through a flue or other obstruction. Said heating unit may be removed when it is not desired to use it during the winter months. -In other words, in winter the additional heat in the kitchen incident to the use of a coal or wood range is desirable and in many cases the electric heat will not be used at all. In s range illustrated is such as to hold down the, heat loss when the oven is used as an electric oven and to keep the electrical operating parts at the lowest temperature possible. This has been accomplished without cutting down the efliciency of the oven when used as a coal oven at which time heat must be transmitted readily through the oven walls inasmuch as the heat comes from without rather than from within the oven.

As contributing to the attainment of the desired results, it will be seen from Figs. 5, 6 and 8, that nearly all metal to metal contact from the oven proper to the metal exterior is eliminated by placing heat insulating material between certain metal parts. The oven proper has no front or rear, being merely a shell 32, open at both ends and provided with castings or angle irons 56, 56' at the front and rear respectively. The front panel or sheet ll of the range comprises the outer enamelled armor therefor and has an inturned flange M. This panel M, as viewed in Fig. 5, constitutes the left hand one of three metal sheets, spaced apart and having asbestos millboard 51 within the two spaces between the same. The middle sheet I4 comprises the front wall or body proper of the range. The innermost sheet I4 is an enamelled sheet or vitrified flue lining to protect the millboard and other body parts from the flue gases and flames. The rear wall l3 of the range, has also a spaced inner sheet or enamelled sheet l3 with asbestos millboard 57 between the two. The front part of the oven projects through an opening in'the middle sheet I 4 but without touching the same, i. e. the horizontal flange of angle iron 56 has a clearance around it. Strips of asbestos millboard 58 are positioned at the rear of the four 'vertical flanges, as shown more clearly in Fig. 8. Similar strips 58 are seen on the rear angle iron 56'. both sets of strips'being held in place during assembly by a suitable adhesive, such for example as silicate of soda. Thus, when the oven is assembled by sliding it rearwardly through the opening in the middle sheet and riveting it at the front and rear, to the front and rear range walls Hi and i3, the front angle iron does not touch said middle sheet because-of .the millboard strips interposed between the two. In like manner the millboard strips 58' prevent contact between the rear flanges 56 and the rear wall I 3. Additional millboard strips 58 are positioned between the vertical flanges of the front angle iron 56 and the front panel including its flange l4.

The outer armor and the inner fiue lining are both assembled after the oven has been put in place and secured by the rivets. Thus there is no metal to metal contact ofv the oven walls (including the angle irons at the front and rear),.

with the exterior walls of the range, except indirectly and to a limited extent, by means of the rivets. The oven is armored with an enamelled sheet 59 on the top and a similar sheet 59' on each side thereof, but not on the bottom, as

shown in Fig. and also in Fig. 6. In addition, heat insulating material is provided in the hollow front door I5.

The left hand side of the oven,,as shown in Fig. 6, is provided with a heat insulating wall 60 which has a horizontal continuation 60' at the upper left hand comer where the fire box casting 36 rests thereon. As previously stated, where heat is developed in the oven, as by means of the electric-heating unit, it is desirable to prevent loss of the same by conduction through the metal walls, whereas the heat conducting propertyof said walls must be utilized to enable the range to operate effectively with coal or wood as the fuel. Since the largest heat loss from the electrically heated oven would be through the metal sides of the oven proper, the design provides an 'air space around said oven, even including the fire box side. The top, right side, left side and bottom are air insulated by virtue of the damper 26, which, when closed by means of the lever 21, insures practically dead air insulation around the oven, which insulation is the most effective known. The rear of the oven is also insulated with dead air which is held in, the flue 25, which flue, as shown by dotted lines in Fig. 6,

covers the left hand portion of the rear of the oven. The right hand rear portion is insulated 'the latter is not completely air-tight in practice,

and the small amount of steam generated in the oven escapes through said vent holes. A broiler heating element 64 may be provided for the upper part of the oven, if desired, although the same is optional as such broilers are not ordinarily provided wherethe range employs coal only. The oven, when heated electrically, may have its temperature controlled by the usual thermostat control 65, shown in Fig. 4. When the oven is heated by the products of combustion and by the electric heater jointly, the thermostatic control varies the current consumption to maintain said oven at the desired temperature. Also,

the .oven door may be provided with a temperature indicator 66 which is useful when the oven is used as a coal or wood oven.

Referring to the electric heaters at the right hand side of the stove and to the chamber bethe chamber 34, a deflector 68 being provided above said drip pan. These right hand burners may be gas burners, in the case of a combination coal and gas range.

The air space above the inclined partition 38 is very much cooler than the flue beneath it due to the fact that fresh air from the vertical duct 42 and switch compartment 43 is continually flowing through said space and out through the openings 5| on three sides whenever there is any heat in the oven. Thus the terminals of the electric heating units are kept reasonably cool.

The conductors from the various heating units in the range are connected to the service wires in the outlet box 69, at the rear, shown in Fig. 4.

The terms left, right", front, "rear, top", bottom, etc., are used in a relative sense to simplify the description and are not intended to be used in a limiting sense, except as necessitated by the prior art.

I claim:

metal walls spaced from the walls of said casing and constituting the inner boundary of a duct, a damper controlling the outlet from said duct, a fuel burning chamber in communication with said duct, and an electric heating unit in said oven, whereby when said damper is closed and the electric heating unit is operating, the air in said duct acts as a heat insulator to reduce the flow of heat outwardly through the walls of said oven, and whereby when said damper is open and the heat for said oven is supplied by fuel, the

products of combustion circulate through said duct and heat said oven by the transfer of heat inwardly through the metal walls thereof, two spaced apart heat insulating partitions between said oven and one of the walls of said range, providing a dead air space, the partition nearest the oven forming one of the walls of said duct, the space between said other partition and the outer wall of said range constituting a fresh air duct having openings near the bottom thereof and a switch box for said electric unit mounted near the top of said fresh air duct, to protect it from the heat.

2. A range having a top and side walls, said top having the usual cooking openings and having also electric heating elements thereon, a single oven in said range, a fire box chamber between said oven and one side wall thereof, a heat insulating partition between said oven and the opposite side wall, a second heat insulating partition between said first partition and said side wall providing a heat insulating air space between said partitions, and providing a fresh air duct between said second partition and outer wall, an inclined partition over said oven joining the top of said first mentioned partition and providing, with the adjacent vertical walls of said range, a heat insulating chamber below said electric heating elements, said chamber having discharge openings near the top thereof, openings in said second partition providing communication between said chamber and said fresh air duct, the latter having additional openings near the bottom thereof whereby cool air may ascend through the same and through said chamber and pass out through said discharge openings.

3. A range having a top and side walls, said top having the usual cooking openings and having also electric heating elements thereon, a single oven in said range, a'flre box chamber between said oven and one side wall thereof, a heat insulating partition, between said oven and the opposite side wall, a second heat insulating partition between said first partition and said side wall providing a heat insulating air space between said partitions, and providing a fresh air duct between said second partition and outer wall, an inclined partition over said oven joining the top of said first mentioned partition and providing, with the adjacent vertical walls of said range, a heat insulating chamber below said electric heating elements, said chamber having discharge openings near the top thereof, openings in said second partition providing communication between said chamber and said fresh air duct, the latter having additional openings near the bottom thereof whereby cool air may ascend through the same and through said chamber and pass 'out through said discharge openings, the upper end of said fresh airduct,

being enlarged to provide a switch compartment, heat insulating material on the inner wall of said compartment, and a switch assembly therein mounted on the outer wall and electrically connected to said heating elements.

4. A combination fuel and electric range comprising an outer metal shell, the top of which has a plurality of cooking openings on one side and a plurality of electric heaters on the other side, an oven arranged substantially centrally in said range, a fire box chamber at one side of said oven beneath said cooking openings, a door concealing said chamber, a substantially similar door on the other side of said oven, whereby a symmetrical arrangement of the top and front of said range is presented, a chamber on the opposite side of said oven the front of which is closed by said similar door, one wall of said chamber being spaced from the adjacent oven wall and extending above and over said oven, joining said top on a line between the cooking openings and the electric heaters to provide, on the oven side, a flue for products" of combustion and to provide on the other side a ventilating space beneath said electric heaters, the other wall of said chamber being spaced from the adjacent outer wall of said range to provide a fresh air flue open at the bottom, said other wall having openings near the top communicating with said ventilating space. v

5. A range having an oven therein with walls of heat conducting material, an electric heating unit in said oven, a fuel grate on one side of said oven, a chamber beneath the top of said range at one side thereof, openings in the walls said fuel grate over, down and under said oven to said rear flue, whereby the heat from the gaseous products of combustion is transferred rapidly through said heat conducting oven walls, said duct having a wall of heat insulating material between it and said fresh air flue, to heat insulate said duct and hence said oven, a damper in the upper part of said rear flue to vary the flow of hot gases around said oven in said duct when said damper is open, and to confine the air in said duct and said flue as a dead air heat insulation,'-when no fuel is burning and said oven is being heated by said electric heating unit.

6. A range as in claim 5, in which said damper is connected to and controlled by a handle projecting above the top of said range at the rear thereof.

7. A range as in claim 5 in which said rear flue partly overlies the rear wall of said oven to insulate the same, and a sheet of heat insulating material covering the remainder of said rear wall.

8. A combination solid fuel and electric range having electric heating elements on one side of the top thereof, an inclined partition within said range joining said top at one end and'extending part way beneath said heating elements, a 'vertical partition joining the other end of said inclined partition thereby forming a chamber on-each side thereof, a grate for solid fuel in one of said chambers, the other chamber serving to minimize the flow of heat from said 

